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connected to different VLANS, when the primary link fails, you will lose access to your management network.

As can be seen, all chassis are connected with their neighbor chassis with redundant connections. The two chassis that

are connected to the top of rack switch are connected to each other, providing a redundant connected path. This

redundant path is important to allow the stack to survive power loss to a full chassis in the middle of the stack.

While the management module contains a concept of “Active” versus “Passive” roles, networking for the chassis’ is

independent of these roles.

The networking algorithm uses Spanning Tree Protocol to determine a network path to each and every component in the

Fab-D stack. This may include forwarding paths through “Passive” MM modules. It is important to note that Spanning

Tree is *not* enabled on any uplink ports to top of rack switches. Spanning Tree is automatically configured between

MX7000 chassis, and is not ever configured on links that are not MX7000 chassis.

One important thing to be aware of are network disruptions caused by cabling or link changes in the stack. When links

change, for example if a cable is pulled or added, the network may go down for approximately 30 seconds to re-compute

the network topology. This affects all chassis in the stack. One thing you will notice is that every time cabling or link state

changes in the stack, all iDRACs and management modules in the stack will reconfigure their network. If the

components are configured for DHCP, you will see them refresh their IP addresses.

The above is true for both DHCPv4 and DHCPv6.

Reserved VLANS

To implement the features for auto uplink detection and network loop prevention, the MX7000 chassis internally use

VLAN in the series 4000 through 4020. This series is reserved by the management module and chassis components

and cannot be used for access through the uplink connection.

All other possible VLANS are available for use and VLAN tagged packets will forward through the stacked chassis.

MX7000 External Port Settings

For all chassis in a stack, it is important that all chassis external port settings are set to the same configuration.

Each management module in the MX7000 chassis has two RJ-45 Ethernet ports labeled “gb1” and “gb2”. Each port is

configured to be Auto MDI-X, which typically eliminates the need for an Ethernet crossover cable when connecting any

MX7000 port to another chassis or top of rack switch. This is a non-configurable setting.

Some port settings, such as speed and auto-negotiation can be configured through the management GUI. All ports on

the chassis will configured with the selected values. When actively changing this chassis setting, there will be a delay in

access while the settings are applied.

Note: If non-auto negotiate settings are selected, the switch that the chassis is connected with MUST be also changed

to the same speed and

duplex values.

Additionally, Auto MDI-X

may not function

properly when auto-

negotiate is off, resulting

in a link down state.

In a dual management

module chassis, all four

external gb1 and gb2

ports are set to the same

settings.

Figure 4 – Management Module Web Page Port Settings